Industrial on-demand exhaust ventilation system with closed-loop regulation of duct air velocities

ABSTRACT

An air pressure measuring ventilation system, comprising: at least one duct; at least one motorized exhaust fan; and one or more air pressure sensors. The at least one motorized exhaust fan may draw air through the at least one duct. The one or more air pressure sensors may be placed on a side of the at least one duct such that an air pressure is measured as the air is drawn through the at least one duct, such that a plurality of air pressure measurements are generated. The one or more air pressure sensors may be substantially flush with an interior side of the at least one duct and do not obstruct the air as the air is drawn through the at least one duct.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a Continuation-in-Part of U.S.Non-Provisional patent application Ser. No. 13/947,616, filed on Jul.22, 2013, titled “Industrial On-Demand Exhaust Ventilation System WithClosed-Loop Regulation of Duct Air Velocities”, by inventor AlesLitomisky, the contents of which are expressly incorporated herein bythis reference as though set forth in their entirety and to whichpriority is claimed.

FIELD OF THE DISCLOSURE

This disclosure relates generally to systems, methods, and devices formeasuring and maintaining air velocity in ducts and ventilation systems.In particular, this disclosure relates to automatically measuring andmaintaining air velocity in ducts in an energy efficient manner withmaterial being transported for industrial exhaust ventilation.

BACKGROUND

The ability to measure air velocity in a duct system has been increasingin importance. Materials being transported in an industrial exhaustventilation system, for instance, are combustible and may be highlyflammable and explosible under certain conditions. One such material iscombustible dust, which is finely divided solid material such asplastic, wood, or metal that presents a fire or explosion hazard whendispersed and ignited in air or any other gaseous oxidizers. Thesecombustible dusts are frequently created as an unwanted by-product andare generally removed from production workspaces as transported materialby a central ventilation system. Due to the combustible nature of thesetransported materials, it is often desirable and important to preventthe transported materials from settling in these ducts. This generallyhelps prevent or lower the risk of combustion occurring in theventilation system. In order to achieve this, it is usually necessary tomaintain minimum transport velocities for the given materials at alltimes and in all ducts of the ventilation system.

The recommended minimum transport velocity for different materials isavailable in A Manual of Recommended Practice, published by AmericanConference of Governmental Industrial Hygienists (ACGIH®). The NationalFire Protection Association (NFPA) has also issued a number ofpublications relating to the prevention of industrial dust explosions.These standards and best practices are generally adopted intoregulations set forth by OSHA, CAL/OSHA, and other state and federalregulatory bodies.

Currently, there is no economically viable air velocity meter on themarket that will measure materials transported through a ventilationsystem such as combustible dust. All currently available cost-effectivevelocity meters only work in clean air and obstruct the transportedmaterial, thereby blocking the duct system and collecting such material.To ensure that the air velocity is above the recommended and relevantstandards, many have measured and recorded the air velocities throughoutthe entire ventilation system during installation. However,manufacturers must regularly change their installation and manufacturingsetup as a result of market changing conditions, including the releaseof new products, the increase of newer more efficient productionmachines, and space constraints and changes.

Additionally, re-measuring the air velocity in duct systems that arechanged, redesigned, or upgraded is not always completed. As a result ofthese constant changes, the air velocities in some ventilation systemducts may become inadequate and may lead to settlement of material. Theair velocities in other parts of the ventilation system may also becometoo high, causing a significant waste of energy. For example, inIndustrial Ventilation Statistics, IETC 2006, written by Ales Litomisky,the measured velocities in the main ducts of 73% of ventilation systemshave been shown to be outside the recommended range.

Due to fast-changing market conditions, manufacturers frequently changetheir manufacturing setup by utilizing an on-demand ventilation system.An on-demand ventilation system generally offers a better alternativethan classic ventilation systems due to the use of sensors, gates,variable frequency drives, and control systems to adjust its system'sperformance.

On-demand ventilation systems also save a significant amount ofelectricity on fan operation compared to classic systems up to 30% to70%. By removing less air from buildings, additional significant savingsin systems that use such air-conditioned systems increase. U.S. Pat. No.7,146,677, issued on Dec. 12, 2006, to co-inventor Ales Litomisky, thesame inventor of the present disclosure, the contents of which areexpressly incorporated herein by this reference as though set forth inits entirety, discloses an energy efficient and on-demand ventilationsystem. U.S. Pat. No. 6,012,199, issued on Jan. 11, 2000, to co-inventorAles Litomisky, is also hereby incorporated by this reference, as thoughset forth herein in its entirety.

In order to adjust and regulate the ventilation system properly,knowledge of air velocities along the length of the entire ventilationsystem while the system is being used is important. This task may bedifficult because no reasonably priced air velocity meters are availableon the market to analyze material being transported in the air. Rather,manufacturers shut down its production and then measure the air flowvelocity, volume, and static air pressure in the ducts of theventilation system. This generally takes several hours of work, atwhich, during this time, the facility or factory stalls its production.Rather, the most commonly used air velocity meters are configured towork on a Pitot tube probe and are evaluated by a precise differentialpressure meter. The Pitot tube generally consists of an impact tubewhich measures velocity pressure input installed inside a second tube ofa larger diameter, which measures static air pressure input from radialsensing holes around the tip. This type of meter is an obstacle for thetransported material and cannot be used during the normal use of a dustexhaust ventilation system.

Other types of air velocity meters work based on “thermal convectivemass flow measurement.” These meters or probes, however, also presentobstacles in the duct, leading to blockage of the material in the ductsystem and damage to the probes.

The third possible alternative to measure air velocity is to use meterswith an ultrasonic transmitter and receiver. Ultrasonic meters, forinstance, are typically used on boats or at airports to measure windspeed. An ultrasonic meter, however, is effectively useless in a ductused to ventilate dust due to the distortion of the ultrasonic signal bythe dust or other transported material. Although it would be possible tomeasure air velocity in a duct based on the laser Doppler principle ortriboelectric effect, such systems would be prohibitively expensive andwould simply not be a viable option.

Accordingly, real-time measurements of air velocity inside the ductsystem that is cost-effective are currently unavailable. Rather, suchreal-time measurements pose a risk of obstruction with dust or othermaterials that are being transported with the air flow in theventilation system.

Thus, what is needed is a cost effective and energy efficient system,method, and device that automatically provides numerous sampling of airvelocity measurements. Preferably, this system, method, and device willmeasure dust and other materials being transported inside the ductsystem during factory production. Furthermore, because most ventilationsystems service multiple work stations that may go online and/or offlineat any moment, a system, method, and device that self regulates andprovides automatic adjustments to the system to maintain an optimal airflow is also needed.

SUMMARY

To minimize the limitations in the cited references, and to minimizeother limitations that will become apparent upon reading andunderstanding the present specification, the present disclosure may bean energy efficient and cost effective system, method, and device formeasuring air flow velocity of material being transported within a ductsystem based on a static air pressure measurement with single pointcalibration or alternatively without necessary calibration.

The ventilation system is part of a factory or facility and ispreferably connected to one or more workstations through one or moredrop ducts. Each drop duct preferably has a gate that, depending on theneeds of the user, opens and closes to ventilate each workstation. Thedrop ducts feed air into branch ducts and then into main ducts, whichterminate at a dust collection unit. The ventilation system ispreferably powered by a fan, which is connected to a motor, wherein themotor is preferably driven by a variable frequency drive. Theventilation system may also include a central control computer orcontrol system (any device with an electronic data processing unit) thatcontrols the opening and closing of gates and fan speed in order toensure that the air flow in all of the ducts is fast enough to preventdust, particles, and any other materials from settling anywhere withinthe ducts. This configuration will also prevent the air from flowing toofast as to waste energy without improving ventilation. The air flow orair volume is preferably kept at optimal levels by: (1) unobtrusivelymonitoring the static air pressure of all relevant locations in theventilation system, (2) calculating the air flow or air volume at themeasured locations, and (3) adjusting the gates and fan speed.

The static air pressure is preferably measured at or near the drop gatesso that the user and control computer may precisely determine the impactof a partial closure of that gate. Additionally, the control computer ispreferably programed to control all the gates based on workstationactivity and the requirements of proper air flow. The desired air flowis preferably provided by standards, which are adopted into variousgovernmental regulations and legislation.

There is preferably only one minimum transport velocity, which isdetermined by type of material transported—very light dust will have forexample 3,500 FPM minimum transport velocity, while heavy dust mighthave 4,500 FPM minimum transport velocity.

One embodiment may be a closed-loop regulation method of a ventilationsystem using a control computer, the steps comprising: providing aventilation system; wherein the ventilation system is comprised of: atleast one duct, at least one motorized exhaust fan, one or more gates;one or more workstations; a control computer, and one or more sensors;wherein each of the one or more workstations has at least one of the oneor more gates; wherein the control computer is configured to open andclose the one or more gates; wherein the control computer is configuredto adjust a speed of the motorized exhaust fan; using the one or moresensors to determine one or more actual air velocities within theventilation system; providing one or more minimum air velocities thatmust be maintained throughout the ventilation system; monitoring by thecontrol computer the one or more air velocities; maintaining by thecontrol computer that the one or more actual air velocities are abovethe relevant minimum air velocity. The maintaining step may beaccomplished by the step of: adjusting by the control computer the speedof the motorized exhaust fan, or by opening and closing the one or moregates by the control computer, or by doing both. Preferably one or moregates are initially closed at the one or more workstations that arenon-active and are initially open at the one or more workstations thatare active. Preferably, the control computer is configured to partiallyopen and partially close the one or more gates in order to accomplishthe maintaining step. Preferably, the method further includes the stepsof balancing by the control computer the one or more actual airvelocities within the at least one duct; calibrating and mapping theventilation system; wherein the user is warned by the ventilation systemfails the calibrating step; and running the ventilation system in one ormore safety modes if the one or more sensors fail.

Another embodiment may be an air pressure measuring ventilation system,comprising: at least one duct; at least one motorized exhaust fan; andone or more air pressure sensors; wherein the at least one motorizedexhaust fan is configured to draw air through the at least one duct;wherein the one or more air pressure sensors are placed on a side of theat least one duct such that an air pressure is measured as the air isdrawn through the at least one duct, such that a plurality of airpressure measurements are generated; wherein the one or more airpressure sensors are configured to be flush with an interior side of theat least one duct and do not obstruct the air as the air is drawnthrough the at least one duct. Preferably the air pressure measuringventilation system further comprises a dust collector and one or moreworkstations and the ventilation system is configured to ventilate dust,particulate matter, or fumes, which are generated at the one or moreworkstations. Because the one or more air pressure sensors are flush,they do not obstruct the dust as it travels along the at least one ductfrom the one or more workstations to the dust collector. The system mayfurther comprise a control computer, also referred to as central controlcomputer, central computer, central processing unit. The plurality ofair pressure measurements are preferably uploaded (via transfer,transmission, or any industrial communication protocol, wired orwireless) to the control computer. The control computer may use theplurality of air pressure measurements to calculate a plurality ofcalculated air velocities. The air pressure measuring ventilation systemmay further comprise one or more gates; wherein the one or more gatesare preferably positioned along the at least one duct between the one ormore workstations and the dust collector; and wherein the controlcomputer is preferably configured to control an opening and a closing ofthe one or more gates and to control a speed of the motorized exhaustfan. The control computer is preferably configured with a plurality ofminimum air velocities that must be maintained. The minimum airvelocities are dependent on the material being moved. The controlcomputer may compare the plurality of calculated air velocities to arelevant minimum air velocity needed as related to the material beingtransported and determines if any of the plurality of calculated airvelocities is less than the relevant minimum air velocity; and if any ofthe plurality of calculated air velocities is less than the relevantminimum air velocity, the control computer adjusts the one or more gatesand adjusts the speed of the motorized exhaust fan such that one or moredeficient air velocities are raised to above the relevant minimum airvelocity that must be maintained.

The control computer preferably compares the plurality of calculated airvelocities to a relevant minimum air velocity as related to the materialbeing transported and determines if any of the plurality of calculatedair velocities is less than the relevant minimum air velocity. If any ofthe plurality of calculated air velocities is less than the relevantminimum air velocity the control computer adjusts the one or more gatesand/or adjusts the speed of the motorized exhaust fan, such that one ormore deficient air velocities are raised to above one or more of theplurality of minimum air velocities that must be maintained.Additionally, the control computer is preferably configured to adjustthe one or more gates and/or adjust the speed of the motorized exhaustfan if any of the plurality of calculated air velocities exceeds anoptimal air velocity, such that the ventilation system is rendered moreenergy efficient. The control computer is preferably configured toautomatically adjust the one or more gates and adjust the speed of themotorized exhaust fan if any of the plurality of calculated airvelocities are not within an optimal range. Preferably the one or moregates is connected to at least one of the one or more air pressuresensors. The plurality of calculated air velocities are preferablycalibrated by taking a plurality of air velocity measurements with aremovable air velocity probe placed substantially near a plurality oflocations of the one or more air pressure sensors. In one embodiment,the air pressure measuring ventilation system may have a sensor with apair of hoses, ends, or openings that are placed on opposite sides ofthe one or more gates (so-called differential pressure sensor), suchthat calibration with a removable air velocity probe is unnecessary.

Another embodiment may be an air pressure measuring ventilation system,comprising: at least one duct; at least one motorized exhaust fan; oneor more air pressure sensors; a dust collector; one or moreworkstations; a control computer; and one or more gates. The at leastone motorized exhaust fan may be configured to draw air through the atleast one duct. The one or more air pressure sensors may be placed on aside of the at least one duct such that an air pressure is measured asthe air is drawn through the at least one duct, such that a plurality ofair pressure measurements are generated. The one or more air pressuresensors may be configured to be substantially flush with an interiorside of the at least one duct and do not obstruct the air as the air isdrawn through the at least one duct. The ventilation system may beconfigured to ventilate a dust that is generated at the one or moreworkstations. Preferably, the one or more air pressure sensors do notobstruct the dust as it travels along the at least one duct from the oneor more workstations to the dust collector. The plurality of airpressure measurements may be used to calculate a plurality of calculatedair velocities. The plurality of calculated air velocities may be sentto the control computer. The one or more gates may be positioned alongthe at least one duct between the one or more workstations and the dustcollector. The control computer may be configured to control an openingand a closing of the one or more gates and to control a speed of themotorized exhaust fan. The control computer may be configured with aplurality of minimum air velocities that must be maintained. The controlcomputer may compare the plurality of calculated air velocities to arelevant minimum air velocity needed as related to the material beingtransported and determines if any of the plurality of calculated airvelocities is less than the relevant minimum air velocity; and, if anyof the plurality of calculated air velocities is less than the relevantminimum air velocity, the control computer adjusts the one or more gatesand adjusts the speed of the motorized exhaust fan such that one or moredeficient air velocities are raised to the relevant air velocity thatmust be maintained. The control computer may be configured to adjust theone or more gates and adjust the speed of the motorized exhaust fan ifany of the plurality of calculated air velocities are not within anoptimal range, such that the ventilation system may be rendered moreenergy efficient. A the plurality of calculated air velocities may becalibrated by taking a plurality of air velocity measurements with aremovable air velocity probe placed substantially near a plurality oflocations of the one or more air pressure sensors. Alternatively, a pairof hoses, ends, or openings from one of the one or more air pressuresensors may be placed on opposite sides of the one or more gates, suchthat calibration with a removable air velocity probe may be unnecessary.

Meaning of adjusting the gates is either partially or fully open, orfully closed. Partially open gate is used for adjusting the air velocityat particular drop, and plurality of the adjustments at plurality ofdrops to adjust airflow in whole branch and in whole system.

Another embodiment may be an air pressure measuring ventilation system,comprising: at least one duct; at least one motorized exhaust fan; oneor more air pressure sensors; and one or more gates. The at least onemotorized exhaust fan may be configured to draw air through the at leastone duct. The one or more air pressure sensors may be placed on a sideof the at least one duct such that an air pressure may be measured asthe air is drawn through the at least one duct, such that a plurality ofair pressure measurements are generated. The one or more air pressuresensors may be configured to be substantially flush with an interiorside of the at least one duct and do not obstruct the air as the air isdrawn through the at least one duct. The one or more gates may bepositioned along the at least one duct, wherein a pair of hoses, ends,or openings from one of the one or more air pressure sensors may beplaced substantially near, and on opposite sides of, the one or moregates, and the one or more air pressure sensors may be configured tomeasure a plurality of air pressure measurements, and the plurality ofair pressure measurements may be used to calculate a plurality ofcalculated air velocities. The plurality of calculated air velocitiesmay be calibrated without needing an external air velocity probe. Theair pressure measuring ventilation system may further comprise a controlcomputer, and the plurality of calculated air velocities may be sent tothe control computer. The control computer may be configured to adjustthe one or more gates and adjust a speed of the motorized exhaust fan ifany of the plurality of calculated air velocities are not within anoptimal range, such that the ventilation system may be rendered moreenergy efficient. The control computer may be configured with aplurality of minimum air velocities that must be maintained. The controlcomputer may compare the plurality of calculated air velocities to arelevant minimum air velocity as related to the material beingtransported, and determines if any of the plurality of calculated airvelocities is less than the relevant minimum air velocity; and if any ofthe plurality of calculated air velocities is less than the relevantminimum air velocity, the control computer adjusts the one or more gatesand adjusts the speed of the motorized exhaust fan such that one or moredeficient air velocities are raised to above of the relevant minimum airvelocity that must be maintained.

Another embodiment may be a method of calculating air velocities withina ventilation system, the steps comprising: providing a ventilationsystem; wherein the ventilation system may be comprised of: at least oneduct, at least one motorized exhaust fan, and one or more air pressuresensors; drawing air through the at least one duct when the at least onemotorized exhaust fan is turned on; wherein the one or more air pressuresensors are placed on a side of the at least one duct; measuring an airpressure by the one or more air pressure sensors as air is drawn throughthe at least one duct, such that a plurality of air pressuremeasurements are generated; and calculating a plurality calculated airvelocities from the plurality of air pressure measurements. The methodmay further comprise the steps of providing a control computer; whereinthe calculating step is performed by the control computer.Alternatively, the steps may further comprise providing a controlcomputer; and providing one or more electronic data processing unitsthat are connected to the one or more air pressure sensors; wherein thecalculating step is performed by the one or more electronic dataprocessing units; transmitting to the control computer a plurality ofcalculated air velocities. Preferably, the one or more air pressuresensors are configured to be flush with an interior side of the at leastone duct and do not obstruct the air as the air is drawn through the atleast one duct. Preferably, the ventilation system further comprises adust collector and one or more workstations and further comprises thesteps of: generating a dust at the one or more workstations; ventilatingby the ventilation system the dust that is generated at the one or moreworkstations; wherein the one or more air pressure sensors do notobstruct the dust as it travels along the at least one duct from the oneor more workstations to the dust collector. The ventilation system mayfurther comprise a control computer and one or more gates; wherein theone or more gates are positioned along the at least one duct between theone or more workstations and the dust collector; and wherein the controlcomputer is configured to control an opening and a closing of the one ormore gates and to control a speed of the motorized exhaust fan.Preferably, the control computer is configured with a plurality ofminimum air velocities that must be maintained. The method may alsoinclude the steps of: comparing by the control computer the plurality ofcalculated air velocities to the relevant minimum air velocity;determining if any of the plurality of calculated air velocities is lessthan the relevant minimum air velocity; and adjusting by the controlcomputer the one or more gates and the speed of the motorized exhaustfan if any of the plurality of calculated air velocities is less thanany of the plurality of minimum air velocities, such that one or moredeficient air velocities are raised to above one or more of theplurality of minimum air velocities that must be maintained. The controlcomputer may compare the plurality of calculated air velocities to arelevant minimum air velocity as related to the material beingtransported, and determines if any of the plurality of calculated airvelocities is less than the relevant minimum air velocity; and if any ofthe plurality of calculated air velocities is less than the relevantminimum air velocity, the control computer adjusts the one or more gatesand adjusts the speed of the motorized exhaust fan such that one or moredeficient air velocities are raised to above one or more of theplurality of minimum air velocities that must be maintained. The methodmay further comprise the steps of adjusting by the control computer theone or more gates and the speed of the motorized exhaust fan if any ofthe plurality of calculated air velocities exceeds an optimal airvelocity, such that the ventilation system is rendered more energyefficient. Preferably each of the one or more gates is connected to atleast one of the one or more air pressure sensors. The method mayfurther comprise the steps of: calibrating the air velocity calculationby taking a plurality of air velocity measurements with a removable airvelocity probe substantially near a plurality of locations of the one ormore air pressure sensors. The calibrating step is preferably performedwith the use of a tablet computer that is wirelessly connected to thesensors and probes. Alternatively the calibration is not necessary ifthe pressure is measured at both sides of the gate (differentialpressure measurement).

It is an object of the system to provide a ventilation system, method,and device that prevents (or essentially prevents) dust or othertransported materials to settle in the ducts of the ventilation system.The ventilation system is preferably also energy efficient and air flowvelocity is usually kept from substantially exceeding a desired maximum.

It is another object of the system to provide a dust/particulate matterventilation system that does not allow dust to settle within any ductsof the system.

It is another object of the system to measure the air flow of theventilation system without obstructing the air flow of the system.

It is another object of the system that the ventilation system maintainsa minimum air flow in all ducts of the system.

It is another object of the system to provide a method ofmeasuring/calculating the air velocity at every outlet (drop) of theexhaust ventilation system with materials being transported in the ductsystem.

It is another object of the system to provide a method of calculatingair velocities in every part of the duct system based on measurementslocated at the duct outlets, the known duct diameters, and the manner,in which the duct outlets are connected together.

It is another object of the system to provide a method of closed-loopregulation by using a central control system, based on known airvelocities in every part of the duct system to ensure proper minimumtransport velocities and outlet air velocities.

It is another object of the system to overcome the limitations of theprior art.

Other features and advantages are inherent in the on-demand exhaustventilation system claimed and disclosed will become apparent to thoseskilled in the art from the following detailed description and itsaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings are of illustrative embodiments. They do not illustrate allembodiments. Other embodiments may be used in addition or instead.Details which may be apparent or unnecessary may be omitted to savespace or for more effective illustration. Some embodiments may bepracticed with additional components or steps and/or without all of thecomponents or steps which are illustrated. When the same numeral appearsin different drawings, it refers to the same or like components orsteps.

FIG. 1 is a representative illustration of one embodiment of theventilation system.

FIGS. 2a-2b are illustrations of one embodiment of an air pressuresensor of the ventilation system.

FIG. 3 is a detailed illustration of a section of duct of one embodimentof the ventilation system, showing a gate and possible locations of anair pressure sensor.

FIGS. 4a-4c are illustrations of one embodiment of the ventilationsystem and shows the possible locations of the workstation gate andrelated air pressure sensor.

FIG. 5 is a graph that shows the relationship between the static airpressure and air velocity within a duct of one embodiment of theventilation system and shows how the length of the drop changes therelationship.

FIG. 6 is an illustration of a duct drop of one embodiment of theventilation system and show the air velocity being taken by a removableair velocity probe.

FIGS. 7a-7b are detailed illustrations of an air velocity probe that isused to calibrate one embodiment of the ventilation system.

FIG. 7c is a detailed illustration of one embodiment of an air pressuresensor that is used to calibrate another embodiment of the ventilationsystem.

FIG. 8 is a schematic illustration of one embodiment of the ventilationsystem and shows possible air pressure, velocity, and volumemeasurements throughout the ventilation system.

FIG. 9 is an illustration of a one embodiment of a gate and air pressuresensor of one embodiment of the ventilation system.

FIG. 10 is an illustration of one embodiment of the ventilation systemand shows how the control computer automatically adjusts the gates andfans to ensure that the air flow is kept above the minimum required.

FIG. 11 is a ventilation duct topology illustration of one embodiment ofthe ventilation system based on the Tree Data Structure.

FIG. 12 is a UML (Unified Modeling Language) software diagram of oneembodiment of the central control computer of the ventilation system.

FIG. 13 is a graph showing the system curves and fan curves that aremeasured and used by central control computer of one embodiment of theventilation system.

DETAILED DESCRIPTION OF THE VARIOUS EMBODIMENTS

In the following detailed description of various embodiments, numerousspecific details are set forth in order to provide a thoroughunderstanding of various aspects of one or more embodiments. However,these embodiments may be practiced without some or all of these specificdetails. In other instances, well-known methods, procedures, and/orcomponents have not been described in detail so as not to unnecessarilyobscure aspects of embodiments of the present disclosure.

While multiple embodiments are disclosed, other embodiments will becomeapparent to those skilled in the art from the following detaileddescription, which shows and describes illustrative embodiments. As willbe realized, the system and method described herein is capable ofmodifications in various obvious aspects, all without departing from thespirit and scope of protection. Accordingly, the graphs, figures, andthe detailed descriptions thereof, are to be regarded as illustrative innature and not restrictive. Also, the reference or non-reference to aparticular embodiment of the disclosure shall not be interpreted tolimit the scope of the disclosure.

In the following description, certain terminology is used to describecertain features of one or more embodiments of the system. For instance,the term “electronic data processing unit” generally refers to anydevice that processes information with an integrated circuit chip,including without limitation, mainframe computers, control computer,embedded computers, workstations, servers, desktop computers, portablecomputers, laptop computers, telephones, smartphones, embeddedcomputers, wireless devices including cellular phones, tablet computers,personal digital assistants, digital media players, portable gameplayers, cloud based computers, and hand-held computers. The term“control computer” is generally any specially-purposed computer orelectronic data processing unit that is integrated into a ventilationsystem and controls the gates, fans, and other mechanical devices ofthat system such that the air velocity and air volumes within the systemare controllable by the control computer.

In the following description, certain terminology is used to describecertain features of one or more embodiments. For purposes of thespecification, unless otherwise specified, the term “substantially”refers to the complete or nearly complete extent or degree of an action,characteristic, property, state, structure, item, or result. Forexample, in one embodiment, an object that is “substantially” locatedwithin a housing would mean that the object is either completely withina housing or nearly completely within a housing. The exact allowabledegree of deviation from absolute completeness may in some cases dependon the specific context. However, generally speaking, the nearness ofcompletion will be so as to have the same overall result as if absoluteand total completion were obtained. The use of “substantially” is alsoequally applicable when used in a negative connotation to refer to thecomplete or near complete lack of an action, characteristic, property,state, structure, item, or result.

As used herein, the terms “approximately” and “about” generally refer toa deviance of within 5% of the indicated number or range of numbers. Inone embodiment, the term “approximately” and “about”, may refer to adeviance of between 1-10% from the indicated number or range of numbers.

Overview of the Ventilation Device

FIG. 1 is a representative illustration of one embodiment of theventilation system. As shown in FIG. 1, the ventilation system 10 ispreferably comprised of a main duct 12, branch ducts 14, drop ducts(also referred to as drops) 16, workstations 18, workstation activitysensor 20, gates 22, dust collector 28, fan 30, motor 32, variablefrequency drive 34, control computer 36, electrical connection 42,filter pressure sensor 50, and fan pressure sensor 52. The gates 22preferably include an air pressure sensor 100, which is shown in FIGS.2a-2b . The fan 30, motor 32, and variable frequency drive 34 arepreferably all components of a motorized exhaust fan, which isconfigured to draw air through the ducts 12, 14, 16, 17. The airpressure sensors 100 are placed on an interior side within the ducts 12,14, 16, such that the air pressure is measured as air is drawn throughthe ducts 12, 14, 16 (shown in FIGS. 2a-2b ).

FIG. 1 shows that the ventilation system 10 preferably ventilates dust,particulate matter, or fumes that are generated at the workstations 18.The dust is collected by the dust collector 28. Although FIG. 1 showsthe gates 22 as being close to the start of the drop, it is preferredthat the gate is at least three duct diameters away from any elbows 17or hoods of workstations 18.

FIG. 1 shows that the ducts increase in diameter size as the ductinggets closer to the fan 30. For example, duct 12 has a smaller diameterthan duct 14. This allows the system to keep the dust or other materialsto keep moving and a minimum velocity to be maintained.

Different Materials

FIGS. 2a-2b are illustrations of one embodiment of an air pressuresensor of the ventilation system. As shown in FIGS. 2a-2b , one or moreair pressure sensors 100 are preferably configured to be flushed 104within an interior side 106 of the duct 16. In this manner, the airpressure sensors 100 preferably do not obstruct the airflow 102 as theairflow 102 is drawn through the duct 12, 14, 16. Because the one ormore air pressure sensors are flushed 104, the air pressure sensorspreferably do not obstruct the dust or cause air turbulence and do notchange air pressure as it travels along at least one of the ducts fromthe one or more workstations 18 to the dust collector 22.

Determining Air Velocity without an Obstructive Probe

The ventilation system is preferably an air velocity measurement andmaintaining ventilation system that preferably includes a sensor formeasuring the static air pressure in a duct. The sensor of theventilation system preferably does not act as an obstacle to thematerial being transported through the duct, as typical airflowmeasuring probes generally act as an obstacle to dust as when air flowtravels through the ducts. As shown in FIGS. 2a-2b , the sensor 100 ofthe ventilation system 10, which is preferably an air pressuremeasurement sensor, may be connected by being flush 104 (orsubstantially flush) with the wall of the ducts 12, 14, 16, such thatthe sensor 100 does not interfere with the air or with the transportedmaterial (dust). The sensor 100 may be located at a point where it isdesirable to have an air velocity measurement, such as the main duct 12or at the drop 16 to a workstation 18, in the branch ducting 14.

FIG. 2b shows the axis of the tap 108 or opening being preferablyperpendicular to the direction of the airflow 102. The tap 108 may beconnected to a pressure sensor mechanism 101 with tubing 110. This typeof sensor 100 is preferably easy to install, inexpensive, and providesaccurate static air pressure sensing at velocities up to 12,000 feet perminute within the ducts 12, 14, 16. For more accurate pressuremeasurements, the tap 108 should have a sharp, burr free opening.Preferably, the tap 108 should be installed in locations withoutturbulence, such as locations that are minimally three duct diametersbehind elbows, hoods, contractions, and the like.

Preferably, the location of the drop pressure reading points may belocated directly within or below a gate 22 in the drop 16. By installingthe sensor 100 at the machine side of the gate 22, the zero-pressurereading also indicates when the gate 22 is fully closed and avoids airturbulence potentially caused by the gate 22.

FIG. 3 is a detailed illustration of a section of duct of one embodimentof the ventilation system, showing a gate and possible locations of anair pressure sensor. As shown in FIG. 3, the sensor 200, 201, 202, 203may be placed above the gate 22, below the gate 22, and/or part of thegate 22. The sensors 200, 201, 202, 203 may have openings to read theair pressure inside the duct 16 and outside the duct 16 in order to geta pressure differential. Gate 22 preferably has blade 23, which is usedto fully or partially close gate 22. The preferred placement is sensor201 and sensor 202. The placement of the sensor 201 and sensor 202directly into the gate 22 may save a lot of work and time duringinstallation of the system. For obtaining a precise air velocitymeasurement, it does not make a difference whether the sensor 100, 200,201, 202, 203 is placed inside the gate 22, in front of the gate 22, orbehind the gate 22. Testing generally shows that the measurement will bethe same regardless of where the sensor 100, 200, 201, 202, 203 islocated along the ducts 12, 14, 16. The location, however, is generallyconsidered when calculating the air velocity.

The preferred purpose of taking the pressure measurement is to calculatethe air velocity (and air volume, if desired) in the duct 12, 14, 16. Inone embodiment, the interpretation of the air velocity from the measuredpressure depends upon: (1) the distance of the ducting (at theworkstation), (2) the pressure measurement probe is located, (3) thediameter and type of the drop ducting (i.e., metal or flexible), and (4)the type of hood—generally on pressure losses between end of the ducting(hood) to point where pressure sensor is installed shortest 400, short401, long 402 (shown in FIGS. 4a-4c ). This interpretation is generallyhandled by determining the “calibration constant” for that location.

In another embodiment, a calibration constant may not need to bedetermined for every location. For example, a calibration constant mayonly need to be determined where the duct varies in diameter. Thecalibration constant(s) may be recorded in a control computer and usedto calculate air velocity measurements to maintain the ventilationsystem.

FIGS. 4a-4c are illustrations of one embodiment of the ventilationsystem and shows the possible locations of the workstation gate andrelated air pressure sensor. As shown in FIGS. 4a-4c , the gate andpressure sensor 422 may be located at numerous locations along thelength of duct 16. FIGS. 4a-4c show that there is a hood 419 between theworkstation 18 and duct 16.

The Air Velocity Formula

In one embodiment, the ventilation system calculates air velocity fromthe formula (or similar formula that is using calibration constant andpressure to calculate the air velocity):

V=K*P ^(0.5323)   Formula [1] where:

V=air velocity (feet per minute (FPM))P=measured static air pressure (inches of water column (“w.c.))K=calibration constant

FIG. 5 is a graph that shows the relationship between the static airpressure and air velocity within a duct of one embodiment of theventilation system and shows how the length of the drop changes therelationship.

Taking the Air Pressure Measurements

In one embodiment, the calibration constant is generally determined foreach measurement point. To obtain the calibration constant, it may benecessary to measure the pressure and air velocity at the same time andthen use Formula V=K*P^(0.5323) to calculate the calibration constant K.After obtaining constant K, the air velocity meter is removed from theducting, and the air velocity may be calculated by taking a measurementof the static air pressure using V=K*P^(0.5323). For purposes of highprecision, the measurements are taken as many times as possible,preferably at least thirty (30) times, and the results are thenaveraged.

In one embodiment, the static air pressure measurements and air velocitymeasurements, which are taken at various locations, including at each ofthe gates in the drops to the workstations, aretransferred—automatically, digitally, remotely, or manually—to a controlcomputer. This control computer preferably calculates and records the Kcalibration constants.

In another embodiment, to calculate the calibration constant, it may benecessary to measure the difference in air pressure (as shown in FIG. 7c). The air pressure measurements may preferably be taken at either sideof a gates (i.e., before the gate and after the gate) and may betransferred—automatically, digitally, remotely, or manually—to a controlcomputer. The control computer may calculate and record an initialcalibration constant K. The control computer may store the measurements,thereby allowing the control computer to calculate additionalventilation system values automatically. In a preferred embodiment, forthe differential pressure measurement, the calibration contact will bemeasured only once (in initial setup) and the calibration constant willbe recorded in the software of the control computer or in anotherembodiment the calibration constant will be recorded directly at thegate processor.

FIG. 6 is an illustration of a duct drop of one embodiment of theventilation system and show the air velocity being taken by a removableair velocity probe. As shown in FIG. 6, measurements of the air velocitymay include airflow 102, pressure sensor installed in the gate 422, duct16, air velocity meter 600, and tablet computer 610. In one embodiment,the K calibration constant is determined by taking the pressuremeasurement via gate and pressure sensor 422 and the air velocitymeasurement via air velocity meter 600 (or probe). A fully automatedmethod of calibration may use, for example a tablet computer 610 thatmay be wirelessly connected to the air velocity meter 600. Here, theuser may place the air velocity meter 600 into the duct 16, may selectthe gate/pressure sensor 422 or other location on the tablet 610, andmay take the calibration measurement. The air velocity meter 600 maythen transfer the air velocity value to the tablet 610, and the tablet610 may transfer the value to the control computer 36, which generallyautomatically calculates the calibration constant K. The pressure valueis then generally transmitted from pressure transmitter to controlcomputer 36. Alternatively, the air velocity meter 600 may not beconnected to the tablet 610—that is, the user may simply read the airvelocity from the meter display and may enter a value to the tablet 610or control computer 36.

Importantly, testing shows that the calculated air velocity is generallyidentical to the measured air velocity at a wide range of air speeds.The precision of the described measurement is more than sufficient forevaluating whether the air velocities in the ducting are above or belowthe necessary minimum transport velocities.

In another embodiment, the air velocity may be calculated without aremovable air velocity meter 600. The air velocity may be calculatedfrom the difference in air pressure measurements before the gate andafter the gate. The difference in air pressure may then be used todetermine an initial calibration constant K. This simplified method ofcalibration may only require the calculation of one calibration constantfor gates installed on ducts of the same diameter. Accordingly, thismethod may avoid calculation of a calibration constant for everylocation, regardless of the diameter of the duct. The measurements maybe recorded and stored in a control computer and used to calculateadditional ventilation system values automatically. In a preferredembodiment, for the differential pressure measurement, the calibrationcontact will be measured only once (in initial setup) and thecalibration constant will be recorded in the software of the controlcomputer or in another embodiment the calibration constant will berecorded directly at the gate processor.

Although several different locations are described where air velocitymeasurements may be taken, it is preferred that these measurements occurat or close to the gates.

FIGS. 7a-7b are detailed illustrations of an air velocity probe(preferably a Pitot probe) that is used to calibrate one embodiment ofthe ventilation system. As shown in FIGS. 7a and 7b , the air velocitymeter 600 is preferably removable from duct 16, so that the air velocitymeter 600 may be removed or inserted for calibration purposes. FIG. 7bshows that the air velocity meter 600 preferably has a probe tip 620that includes an opening 630 to read velocity pressure and static sensoropenings 640. The air flow 650 may be directed to air velocity sensormechanism, which preferably determines and, preferably records the airvelocity measurements.

FIG. 7c is a detailed illustration of an air pressure sensor that isused to calibrate another embodiment of the ventilation system. As shownin FIG. 7c , an air pressure sensor 700 may be configured to be near agate with two ends or hoses 720, 725 that are flush within an interiorside of the duct 705. In this manner, the air pressure sensor 700preferably does not obstruct the airflow 710 as the airflow 710 is drawnthrough the duct 705. Because the air pressure sensor 700 is flush, theair pressure sensor 700 preferably does not obstruct the dust or causeair turbulence and the ends/hoses/openings 720, 725 themselves do notthemselves cause a change in air pressure as it travels along the ductsfrom the one or more workstations to the dust collector. The airpressure sensors 700 may be located at a point where it is desirable tohave an air velocity measurement, such as substantially near a gate 715.Preferably, the air pressure sensor 700 may comprise two ends, hoses, oropenings 720 and 725, so that the sensor 700 may read air pressuremeasurements before and after the gate 715. The difference in airpressure 730 may then be used to calculate the air velocity based on theformula or the table built-in the control computer or at the processingunit at the pressure sensor (or at the gate).

The embodiment shown in FIGS. 6 and 7 a, may require that the airvelocity be measured with the external meter/sensor, as shown in FIG. 6,and that measured value is entered to the control computer. Theembodiment shown in FIG. 7c preferably does not require such calibrationwith the external air velocity meter. This simplifies installation andsetup of the system, if the sensors shown in FIG. 7c are installedsystem wide. This embodiment allows the creation of software for thecontrol computer to setup the system ventilation values (air velocities)fully automatically. Another advantage of this embodiment is that thesystem will maintain ventilation values, even if the system losses arechanged, such as those caused by (a) clean or dirty filter losses, or(b) winter or summer operation. During winter operation the clean airmay be returned to the building via additional filter that will increasepressure losses. Another advantage of this embodiment is thatinstallation time is saved because it is not necessary to calibrate theair velocity reading for every installed gate for every installedworkstation. This makes the installation more cost effective.

In the embodiment shown in FIG. 7c , the pressure/velocity measurementwill only require each model of the gate for different diameters of theduct to be calibrated once, during research and development/initialset-up. Subsequently these measurements will be included in the controlcomputer in the form of a conversion table or as a formula. Themeasurements, may be recorded and stored in a control computer and usedto calculate additional ventilation system values automatically.

Displaying the Air Velocities and Air Volumes

The measured air velocities are preferably displayed in various text andgraphic forms at the displays that are connected to or linked with thecentral computer. The preferable method is to display air velocities asa graphical representation of a duct-layout/ventilation system on thecomputer screen(s) or display(s) that are connected to or linked withthe system. This graphical representation of the ventilation systempreferably mimics the real duct layout of the factory, so that a usermay quickly see the performance of the system at each location. This ispreferably the easiest way for a user to understand air velocitiesthroughout the entire system. In addition, the display is preferablycolor-coded to aid the user in quickly recognizing inadequatevelocities. In one embodiment a green background may signify airvelocities within the proper range; a red background may indicate lowair velocity; and a blue background may represent air velocities thatare too high.

FIG. 8 is a schematic illustration of one embodiment of the ventilationsystem and shows various air flow statistics throughout the ventilationsystem as might be displayed on the computer screen(s) or display(s) ofthe ventilation system.

The Air Volume Formula

The control computer 36 may also display values of the air volume ateach measurement point, such as the gates or drops, by using the ductdiameter (preferably entered during system setup by user) and by usingthe following formula:

U=A*V   Formula [2]

wherein:U=Air Volume (cubic feet per minute (CFM))A=area of the particular duct (square feet (sqft))

V=Air Velocity (FPM) (Calculated)

wherein:A is generally calculated from the duct diameter through the followingformula:

A=π(d/2)²   Formula [3]

wherein:

D=the diameter of the duct at the measurement point (feet)

Displaying air volume instead of or in addition to the air velocity ishelpful in certain industries, such as the pharmaceutical industry,where design values are typically specified in air volumes.

Closing and Opening the Gates

The gates used within the on-demand ventilation system may be based onvarious principles. One embodiment may use pneumatically operated gates,with linear or rotating blades while another embodiment may useelectrically operated gates, with linear or rotating blades. Otherindustries typically use “butterfly” gates. Thus, despite the type ofgate that is used, any gate may be used by the ventilation system, solong as they can be open and closed automatically.

The preferred location for installing the static air pressure probe isthe collar of the gate. The collar of the gate is used to connect thegate to the duct system. Preferably, the pressure probe is installed onthe machine-facing collar, as opposed to the fan facing collar. Wheninstalled this way, the pressure reading preferably drops to zero whenthe gate is closed. This preferably indicates that the gate is properlyand fully closed, which aids in detecting gate errors. Additionally,some industries that handle poisonous gasses, dangerous substances, orcontrolled substances require positive confirmation of properventilation, which is typically aided by having the pressure sensorinstalled in the machine-facing collar to confirm the flow when the gateis open. Another embodiment of the pressure measurement can be donebetween both gate collars. This approach may allow the system tocalculate the air velocity without the calibration of the external airvelocity meter.

Because the maximum benefit for the measurement of air velocities isobtained if the air velocities are measured at each drop and branch ofthe duct system, the pressure sensors are preferably connected at thegate's electronics. If the gate is not using an electronic board, thepressure sensor may be connected to a standalone electronic board. Thegate electronic board (or the standalone controller) preferablycommunicates with the central control computer. Further, the gates inon-demand ventilation systems are typically connected to the centralcontrol unit, and can transfer data to the central control unit,typically via various types of the wired field bus industrial protocols,or industrial wireless protocols.

FIG. 9 is an illustration of a one embodiment of a gate and air pressuresensor of one embodiment of the ventilation system. As shown in FIG. 9,the gate and air pressure sensor 422 is preferably comprised of gate 22,blade 23, air pressure sensor mechanism 101, tubing 110, flush mount104, blade motor 998, control board 905, air pressure sensor device 907,and connection 908 to control computer 36. The control computer 36 maycontrol blade motor 998 through connection 999.

Maintaining Minimum Air Velocity

The central control computer generally uses the measured airvelocity/air volume values to adjust the system to exhaust the requiredair volume and to maintain proper air velocities in each part of theduct system. The required air velocity/air volume for each workstationand for the duct system is preferably entered into the computer, and therequired air velocity/air volume may also be calibrated based uponrelevant standards, regulations, and legislation governing the materialbeing ventilated and/or worked on at the work station. The branchdiameters and the main duct diameters may also entered into the controlcomputer, and the system preferably has activity sensors, which arepreferably connected to all the workstations, to inform the system as towhich workstations currently require ventilation. For example, when thesystem is on, pressure measurements may be taken from the variouslocations of the pressure sensors within the system. Using FormulaV=K*P^(0.5323), the air velocity is calculated at each sensor. Also,when using Formulas U=A*V and A=π*(d/2)², the control computer maydetermine the air volume at each location. The air volume (or airvelocity) is generally then compared to the minimum air volume (orvelocity) required by the standards, and if the calculated volume orvelocity at any location is less than what is required, the controlcomputer may recognize this and adjusts the fan and gates,accordingly—that is, to increase the air volume or velocity. Conversely,if the air volume or velocity is too great, and thus, energyinefficient, the control computer may recognize this and adjusts the fanand gates accordingly. The description how the control computer adjuststhe gates and the fan speed is detailed below.

In addition to determining the volume of air flow needed at each sensorlocation, the control computer may also calculate the total air volumecurrently required by the system using the following equation:

U=Σ _(i=1) ^(n) S _(i) ·U _(i)   Formula [4]

where: Si=logic value (0 or 1) of the workstation activity sensors (onor off)Ui=minimum required air volume of that work stationn=total number of workstations in the system

This generally allows the control computer to determine the baseline fanspeed depending on how many workstations are in use.

FIG. 10 is an illustration of one embodiment of the ventilation systemand shows how the control computer automatically adjusts the gates andfans to ensure that the air flow is kept above the minimum required. Asshown in FIG. 10, the system preferably includes fan 30, variablefrequency drive 34, control computer 36, gates 22 (#1, 2, and XXX), airpressure sensor mechanisms 101 (#s 1, 2, and XXX), workstation activitysensors 20 (#s 1, 2, and XXX), and connections 908. FIG. 10 shows howthe central control computer 36 is able to control the gates 22 and fan30 to keep the air flow above the minimum and keeps the system energyefficient. XXX herein means that very high number of the gates(workstations, pressure sensors) can be connected and/or used in oneventilation system.

Method of Calculating Air Velocities in Every Part of the Duct SystemBased on Measurements at the Duct Outlets

The air velocity in every part of the duct system may be calculated ifthe air velocity at each duct, the duct diameters, and the manner inwhich the ducts are connected together (i.e., the duct system topology)are known. One of the methods to store and model the duct systembranching layout in a control computer is preferably a Tree DataStructure, which is well known in the art. A Tree Data Structure isgenerally a hierarchical tree structure, with a root value and sub treesof children, represented as a set of linked nodes.

FIG. 11 is a topology illustration of one embodiment of the ventilationsystem based on the Tree Data Structure. As shown in FIG. 11, circlenodes 700 (F and 1-8) and links 702 (1-8) form a hierarchical treestructure, with a root value and sub trees of children. In thisconfiguration, each node 700 (F and 1-8) generally represents a branchof ducting and is usually defined by the value of air velocity and airvolume together with a list of connected child nodes. Circle node F isthe exhaust ventilation fan and circle node 1 is the main duct, or rootnode. Each node generally represents the branch of ducting leading fromitself to its parent node, and each node may be defined by the value ofair velocity and air volume. However, other considerations may beincluded, such as duct diameter. Each node in FIG. 11 may be showntogether with a list of connected child nodes, if any. As shown in FIG.11, child nodes 700 #7 and 700 #8 represent two outlets (typically,drops to workstations) of the duct system, with no children ductsconnected to them. Because the system preferably measures the airvelocity at each duct outlet and may calculate air volume, both the airvelocity and air volume at nodes 700 #7 and 700 #8 are known, whichallows the air velocity and air volume at node 700 #3 to be calculatedusing the following formula: U3=U7+U8. The air velocity at node 700 #3can be calculated from U3 and node 3 diameters. By applying this method,we can calculate the air volume and air velocity in every node (duct) ofthe entire system up to the main duct and fan. As shown in FIG. 11, itis preferred that no reference to a child node is duplicated and noreference points to the root. The FIG. 11 shows that measured values ofthe air velocity at each drop and known dust system topology allowscalculating the air velocities in each part of the duct system.

Method of Closed-Loop Regulation Using a Central Control Computer

As discussed above, the air velocities and/or air volumes are known (viameasurement or calculation) in every part of the ventilation system.These known air velocities and/or air volumes are used within anon-demand ventilation system that close (or open) gates at non-activeworkstations, with the goal of maintaining air velocity and savingelectricity on the operation of the exhaust fan (and on make-up air, ifair-conditioning is used—because with on-demand system less air isexhausted out of building then less of make-up air system can beproduced; the make-up air savings is significant in certain industriessuch as pharmaceutical industry where make-up air must be extremelyclean and is very expensive). Because closing various gates reduces thetotal required air volume, and thus, energy use of the system, it ispreferred that two conditions be fulfilled:

a. First, the minimum air velocity in the entire duct system must bemaintained to avoid material/dust settling and becoming a hazard.b. Second, the air velocity at the outlets (drops) should be above therecommended drop velocity of the material/dust being transported so asto provide effective ventilation.

Generally, the minimum dust transport velocity and the outlet velocityvalues differ from each other, with the minimum transport velocitygenerally being lower. For example, the minimum transport velocity forfine dry sawdust is generally 3,500 FPM, while the recommended outletvelocity is 4,500 FPM. These are simplified example values, and theactual velocity values may differ. Although the ventilation systempreferably works with air velocity at any velocity, for practicalpurposes, the air velocities in the main duct and branch ducts aregenerally at least above the minimum transport velocity of thedust/material, for example 3,500 FPM (for dry fine sawdust). Airvelocities in the main duct and branch ducting above 6,500 FPM areimpractical because the pressure losses become too high for theinstalled fan.

Before the on-demand ventilation system is operated in automatic mode,the calibration and mapping routine may be performed. During thecalibration routine, the fan and system curves (shown in FIG. 12) shouldbe measured and the system may be optimally mapped to the fan curve. Thecalibration data is preferably evaluated for a match between the fancurve and the system curve; the fan may also be evaluated for maximalair volume necessary to operate all workstations above the minimum airflow requirements throughout the ventilation system. The static pressurestall region of the fan may also be measured. The fan, preferably,should not be operated in this area due to excessive vibration and noisewhich generally represents a danger and may destabilize the entireventilation system. If proper mapping is not possible, the ventilationsystem may inform the user that the ventilation system may not unable tobe used in the automatic mode. The control computer in a first stepmeasures the system curve with all gates open (as shown in FIG. 13). Thecontrol computer may open all gates and increase fan RPM from minimalspeed to maximal speed in the increments for example 1 Hz At each stepthe control computer will measure air volume and fan total pressure asshown in FIG. 13. Then the control computer will repeat the same systemcurve measurement with a certain percentage of the gates closed. Forexample, four different system curves can be measured for four differentpercentages of the gates closed to model how the dust collecting systemwill typically be used. Alternatively if the duct system uses severalmajor branches, the measurement may be taken with only branch #1 openand a second measurement only with branch #2 open, and so on.

The system curves are mathematically simple, therefore they can bemodeled formula P=L*e^(MU) where P is pressure, L and M are constantsand U is measured air volume. The sets of the system models can be usedfor the safety mode as described below.

The next step is preferably the measurement of the fan curve at full fanspeed and with all gates open. The control computer will keep takingthis measurement at the same fan speed (for example 60 Hz) and willstart closing gates one by one and measure in each change in air volumeand fan total pressure. This step will be repeated by using differentfan speeds, for example, the fan curve may be measured at 60, 50, 40,and 30 Hz.

After measuring the system and fan curves, the control computerdetermines the best mapping of the system to the fan curves. As a firststep during mapping system will open all gates and will change the fancurve (fan speed) until the required air volume will match measured airvolume, then the control computer will close, for example, 10% of thegates, and then the control computer will again determine at which fancurve the measured air volume matches the required air volume. Theseselected fan curves will preferably be used in the safety mode asdescribed below. The safety mode is not using close-loop regulation, buta predetermined open-loop regulation.

The ventilation system is preferably designed so that when all of theworkstations are active, and thus, all the gates open, the outlet airvelocities should be optimal and balanced (i.e. at the required valuesat each outlet). With all of the gates open, it is generally practicalfor the on-demand ventilation system to use high air velocities in themain duct and branch ducts. For example, in the woodworking industry,the practical maximum air velocity in the main duct with all gates openmay be 6,500 FPM. Using high velocities in the main duct and brancheswith all gates open generally increases the pressure losses butgenerally allows the system to operate with lower air volume when onlysome of the workstations are active. Choosing a proper range of airvelocities for the ventilation system is a balancing act wherein somethe most critical information to know is the average and peakutilization of the workstations. The preferred goal is generally toensure that the ventilation system is the most energy efficient most oftime. For example, if the average utilization of the workstations is low(e.g., 50-60%) it may be preferable to use higher air velocities in themain duct and branch ducts when all gates are open. If the averageworkstation utilization is relatively high (e.g., 80-90%) it is usuallybetter to use lower air velocities when all gates open.

Regulation of the Ventilation System for Times when not all Workstationsare being Used

FIG. 12 is a flow block diagram of one embodiment of the ventilationsystem. As shown in FIG. 12, the closed-loop regulation method toachieve proper air velocities at outlets and in the entire duct systempreferably is comprised of the activities, or steps, which arepreferably executed at control computer in parallel (at a same time):(1) measure and/or calculate the air velocity and volume in each part ofthe duct system 904; (2) opening/closing gates at active/non-activeworkstations 906; (3) regulating all active duct outlets 908; (4)monitoring minimum transport velocities 910; (5) balancing duct zones912; (6) verifying all sensors and gates 920; and (7) warning the user922 if necessary. FIG. 12 also shows that these regulation steps, oractivities, may be executed in parallel and preferably at the centralcontrol computer. As shown in FIG. 12, the system is generally initiallycalibrated and mapped 900. If there is a calibration failure, the systemwarns the user of the failure, such as that the fan and system do notmatch 902. The system calibration and mapping is described above.

Once calibration is successful, the first step or activity (it ispreferable refer to the steps as activity, because the steps are notnecessarily completed in succession, but may be done in parallel) oractivity is to measure and/or calculate the air velocity and volume 904.This is preferably is done in accordance with the measurement andcalculation methods described herein. In the second step, the controlunits generally opens and/or closes the gates at the active and/ornon-active workstations 906; wherein the active workstation is generallyopen, and the non-active workstation is generally closed. The third stepgenerally involves regulating all active outlets 908. The PID(proportional-integral-derivative) generally regulates the system, andthe control computer monitors all outlet air velocities. These airvelocities are preferably one or more measured and/or calculated valuesas described herein. The outlet air velocities are preferably above therequired minimum outlet air velocity, and if any outlet air velocitiesare below the minimum, the speed of the fan is preferably increased.Alternatively, or in conjunction, the control computer may partiallyclose one or more gates at outlets with higher than desired outlet airvelocities. Partially closing one or more of the gates may likelyincrease pressure losses at these outlets, and, thus, redirect air tooutlets with lower air velocities. This approach is generally availableonly for use with very fine dust or fumes (therefore applicable incertain industries such as pharmaceutical, welding), wherein thepartially closed gate will not cause material jamming inside the ducts.If the air velocities in all of the outlets are too high, the fan speedis preferably decreased. Decreasing and increasing air velocities maypreferably be based on proportional-integral-derivative controllerregulation to eliminate, substantially eliminate, and/or reduce thesystem's oscillation. In the fourth step (i.e., monitoring minimumtransport velocities 910), the system generally monitors the minimumtransport velocities by opening and/or closing workstation gates (childnodes). In the event that the number of active workstations causes theair velocities in certain parts of the ducting of the ventilation systemto drop below the minimum transport air velocity, the central controlcomputer preferably opens gates on non-active workstations at childrennodes. This generally involves the child nodes that are closest to theducting with the inadequate air velocities. In step 5 (i.e., balancingduct zones 912), the system generally balances the duct zones 912.Specifically, if the air velocities in two neighboring branches of ductsdiffer (e.g., one duct being too high while the other duct is too low),the system may close, partially or fully, some other additional opengates that are located at non-active workstations. This generallyincreases the pressure losses in that branch, resulting in a higher airflow into the other branch. The system may include another step oractivity, which is not shown in FIG. 12 because this step or activity isgenerally undertaken only when a small percentage of workstations areactive. Specifically, the appropriate air volume generally may beachieved at a relatively low fan speed. A low fan speed, based on fancurves, may lead to inadequate total fan pressure to overcome the systempressure loses, and in this case, it may be possible to increase the fanspeed to move to a higher level fan curve, wherein the fan generates ahigher total pressure. This, in turn, may increase the electricityconsumption of the fan, but generally only insignificantly, therebyreducing energy consumption.

FIG. 12 also shows that it may be preferable to add two additionalsafety modes that are enabled in case of error, which may reflected instep 6 and step 7 (i.e., verifying all sensors and gates 920 and warningthe user 922, respectively). In these steps, the system preferablyverifies that all gates and sensors are working. If the systemdetermines that one of the gates or sensors is not working properly, thesystem will preferably issue a warning and put the system into SafetyMode 1 or 2. Similar safety modes are built-into the control units forcar engines, and if some sensors are not working properly, the controlunit will preferably allow the car to be used in safety mode—and drivehome or to a service center with limited maximal engine output. If thecentral computer cannot get reliable measurements from a sensor,however, the control computer will switch to Safety Mode 1.Specifically, in Safety Mode 1, the system generally adjusts the fan airvolume based on a percentage of the gates currently open (this mode mapsthe system curve to fan curve during the initial calibration and mappingroutine) and an algorithm that opens a certain percentage of the gatesin each duct zone to maintain minimum air flow is preferably used. Byusing Safety Mode 1, the system may be operated until the malfunctioningsensor can be repaired or replaced.

On the other hand, Safety Mode 2 is more radical. In Safety Mode 2 thesystem opens all gates and generally operates the fan at maximum speed.In this configuration, the system is operated like a standard exhaustventilation system, and the proper air velocities are set by properdesign of the duct system by matching the fan curve to the system curve,as shown in FIG. 13.

FIG. 13 is a graph showing the fan curves and system curves (the fancurves and system curves are official names of thesemeasurements/charts) of air volume to fan total pressure of oneembodiment of the ventilation system. As shown in FIG. 13 the fan curvesare shown plotted against the system curves ranging from all gates opento some percentage of gates closed. Specifically, the more gates thatare closed, the higher the total fan pressure. The system curves and fancurves are measured in the initial system calibration and mappingprocedure as described previously and used for system regulation insafety modes 1 and 2.

Unless otherwise stated, all measurements, values, ratings, positions,magnitudes, sizes, locations, and other specifications that are setforth in this specification, including in the claims that follow, areapproximate, not exact. They are intended to have a reasonable rangethat is consistent with the functions to which they relate and with whatis customary in the art to which they pertain.

The foregoing description of the preferred embodiment has been presentedfor the purposes of illustration and description. While multipleembodiments are disclosed, still other embodiments will become apparentto those skilled in the art from the above detailed description. Thedisclosed embodiments capable of modifications in various obviousaspects, all without departing from the spirit and scope of theprotection. Accordingly, the detailed description is to be regarded asillustrative in nature and not restrictive. Also, although notexplicitly recited, one or more embodiments may be practiced incombination or conjunction with one another. Furthermore, the referenceor non-reference to a particular embodiment shall not be interpreted tolimit the scope. It is intended that the scope or protection not belimited by this detailed description, but by the claims and theequivalents to the claims that are appended hereto.

Except as stated immediately above, nothing that has been stated orillustrated is intended or should be interpreted to cause a dedicationof any component, step, feature, object, benefit, advantage, orequivalent, to the public, regardless of whether it is or is not recitedin the claims.

What is claimed is:
 1. An air pressure measuring ventilation system,comprising: at least one duct; at least one motorized exhaust fan; andone or more air pressure sensors; wherein said at least one motorizedexhaust fan is configured to draw air through said at least one duct;wherein said one or more air pressure sensors are located on a side ofsaid at least one duct such that an air pressure is measured as said airis drawn through said at least one duct, such that a plurality of airpressure measurements are generated; and wherein said one or more airpressure sensors are substantially flush with an interior side of saidat least one duct and do not obstruct said air as said air is drawnthrough said at least one duct.
 2. The air pressure measuringventilation system of claim 1, further comprising a dust collector; andone or more workstations; wherein said ventilation system is configuredto ventilate a dust that is generated at said one or more workstations;and wherein said one or more air pressure sensors do not obstruct saiddust as it travels through said at least one duct from said one or moreworkstations to said dust collector.
 3. The air pressure measuringventilation system of claim 2, further comprising a control computer;wherein said plurality of air pressure measurements are uploaded to saidcontrol computer; and wherein said control computer uses said pluralityof air pressure measurements to calculate a plurality of calculated airvelocities.
 4. The air pressure measuring ventilation system of claim 2,further comprising a control computer; wherein said plurality of airpressure measurements are used to calculate a plurality of calculatedair velocities; and wherein said plurality of calculated air velocitiesare sent to said control computer.
 5. The air pressure measuringventilation system of claim 4, further comprising one or more gates;wherein said one or more gates are positioned along said at least oneduct between said one or more workstations and said dust collector; andwherein said control computer is configured to control an opening and aclosing of said one or more gates and to control a speed of saidmotorized exhaust fan.
 6. The air pressure measuring ventilation systemof claim 5, wherein said control computer is programmed with a pluralityof minimum air velocities that must be maintained, depending on amaterial being transported by the system; wherein said control computercompares said plurality of calculated air velocities to a relevantminimum air velocity and determines if any of said plurality ofcalculated air velocities is less than said relevant minimum airvelocity; wherein said relevant minimum air velocity is dependent onsaid material being transported by the system; and wherein if any ofsaid plurality of calculated air velocities is less than said relevantminimum air velocity, said control computer adjusts said one or moregates and adjusts said speed of said at least one motorized exhaust fansuch that said plurality of calculated air velocities are raised toabove one or more of said plurality of minimum air velocities that mustbe maintained.
 7. The air pressure measuring ventilation system of claim6, wherein said control computer is configured to adjust said one ormore gates and adjust said speed of said motorized exhaust fan if any ofsaid plurality of calculated air velocities exceeds an optimal airvelocity.
 8. The air pressure measuring ventilation system of claim 5,wherein said control computer is configured to automatically adjust saidone or more gates and adjust said speed of said motorized exhaust fan ifany of said plurality of calculated air velocities are not within anoptimal range.
 9. The air pressure measuring ventilation system of claim8, wherein a said plurality of calculated air velocities are calibratedby taking a plurality of air velocity measurements with a removable airvelocity probe placed substantially near a plurality of locations ofsaid one or more air pressure sensors.
 10. The air pressure measuringventilation system of claim 8, wherein one of said one or more airpressure sensors is placed proximate to said one or more gates, suchthat two hoses of said sensor are on opposite sides of said one or moregates, and such that calibration with a removable air velocity probe isunnecessary.
 11. An air pressure measuring ventilation system,comprising: at least one duct; at least one motorized exhaust fan; oneor more air pressure sensors; a dust collector; one or moreworkstations; a control computer; and one or more gates; wherein said atleast one motorized exhaust fan is configured to draw air through saidat least one duct; wherein said one or more air pressure sensors areplaced on a side of said at least one duct such that an air pressure ismeasured as said air is drawn through said at least one duct, such thata plurality of air pressure measurements are generated; wherein said oneor more air pressure sensors are configured to be substantially flushwith an interior side of said at least one duct and do not obstruct saidair as said air is drawn through said at least one duct; wherein saidventilation system is configured to ventilate a dust that is generatedat said one or more workstations; wherein said one or more air pressuresensors do not obstruct said dust as it travels along said at least oneduct from said one or more workstations to said dust collector; whereinsaid plurality of air pressure measurements are used to calculate aplurality of calculated air velocities; wherein said plurality ofcalculated air velocities are sent to said control computer; whereinsaid one or more gates are positioned along said at least one ductbetween said one or more workstations and said dust collector; whereinsaid control computer is configured to control an opening and a closingof said one or more gates and to control a speed of said motorizedexhaust fan; wherein said control computer is configured with aplurality of minimum air velocities that must be maintained; whereinsaid control computer compares said plurality of calculated airvelocities to said a relevant minimum air velocity and determines if anyof said plurality of calculated air velocities is less than saidrelevant minimum air velocity; and wherein if any of said plurality ofcalculated air velocities is less than said relevant minimum airvelocity, said control computer adjusts said one or more gates andadjusts said speed of said motorized exhaust fan such that saidplurality of calculated air velocities are raised to above said relevantminimum air velocity that must be maintained.
 12. The air pressuremeasuring ventilation system of claim 11, wherein said control computeris configured to adjust said one or more gates and adjust said speed ofsaid motorized exhaust fan if any of said plurality of calculated airvelocities are not within an optimal range.
 13. The air pressuremeasuring ventilation system of claim 12, wherein a said plurality ofcalculated air velocities are calibrated by taking a plurality of airvelocity measurements with a removable air velocity probe placedsubstantially near a plurality of locations of said one or more airpressure sensors.
 14. The air pressure measuring ventilation system ofclaim 12, wherein one of said one or more air pressure sensors is placedproximate to said one or more gates, such that two hoses of said sensorare on opposite sides of said one or more gates, and such thatcalibration with a removable air velocity probe is unnecessary.
 15. Anair pressure measuring ventilation system, comprising: at least oneduct; at least one motorized exhaust fan; one or more air pressuresensors; and one or more gates; wherein said at least one motorizedexhaust fan is configured to draw air through said at least one duct;wherein said one or more air pressure sensors are placed on a side ofsaid at least one duct such that an air pressure is measured as said airis drawn through said at least one duct, such that a plurality of airpressure measurements are generated; and wherein said one or more airpressure sensors are configured to be substantially flush with aninterior side of said at least one duct and do not obstruct said air assaid air is drawn through said at least one duct; wherein said one ormore gates are positioned along said at least one duct; wherein at leastone of said one or more air pressure sensors is placed substantiallynear said one or more gates, such that two hoses of said sensor are onopposite sides of said one or more gates, and such that calibration witha removable air velocity probe is unnecessary; wherein said one or moreair pressure sensors are configured to measure a plurality of airpressure measurements; and wherein said plurality of air pressuremeasurements are used to calculate a plurality of calculated airvelocities.
 16. The air pressure measuring ventilation system of claim15, wherein a said plurality of calculated air velocities are calibratedwithout needing an external air velocity probe.
 17. The air pressuremeasuring ventilation system of claim 15, further comprising a controlcomputer; wherein said plurality of calculated air velocities are sentto said control computer.
 18. The air pressure measuring ventilationsystem of claim 17, wherein said control computer is configured toadjust said one or more gates and adjust a speed of said motorizedexhaust fan if any of said plurality of calculated air velocities arenot within an optimal range.
 19. The air pressure measuring ventilationsystem of claim 17, wherein said control computer is configured with aplurality of minimum air velocities that must be maintained; whereinsaid control computer compares said plurality of calculated airvelocities to a relevant minimum air velocity and determines if any ofsaid plurality of calculated air velocities is less than said relevantminimum air velocity; and wherein if any of said plurality of calculatedair velocities is less than said relevant minimum air velocity, saidcontrol computer adjusts said one or more gates and adjusts said speedof said motorized exhaust fan such that one or more deficient airvelocities are raised to above said relevant minimum air velocities thatmust be maintained.